I'm way behind you guys in catching up to this thread and forgive me if this has already been said, but just want to point out that New Carrollton is a point of access to lots of public transportation possibilities: Amtrak, MARC (DC-Baltimore-Frederick), and loads of various buses that go to cities Northeast of DC - Philly, NYC, New Haven, Hartford, Springfield, Boston, Concord - and Northwest - Allentown, Morgantown, Pittsburgh, Cincinnati, etc. etc. Also, can take routes South to link up to VRE (Virginia Rail Express) or other points of access. And of course the metro (though I doubt the perps would be needing that mode of transport at the moment). In my opinion, mostly because I'm familiar with the region, the suspects going to New Carrollton makes a lot of sense to me if they needed to get out of the DC metro area fast, cheaply, and able to travel undetected.
Point well taken.